1. Field of the Invention
This invention relates to a method of mediating a biofeedback session with a human subject in which measurements of certain of the subject's electrophysiological parameters are used to control the presentation to the subject of a series of prestored audiovisual sequences of varying levels of clarity or perspective to provide targets whose viewing induces in the subject a desired psychological state. Specifically, the present invention relates to the control of the speed of relative motion of the visual portion of the sequence and the audio content of the sequence.
2. Description of the Prior Art
Biofeedback is a process in which electrodes are connected to a human subject to monitor electrophysiological parameters such as heart rate, electroencephalographic signals and galvanic skin resistance. These signals are converted to a visual or audio display that can been seen and/or heard by the subject, who attempts to alter the parameters using the display as a guide to his progress. If it is desirable to reduce blood pressure, for example, the display may consist of a bar graph indicating the magnitude of the pressure. If the subject is successful in lowering his blood pressure, he will see the size of the bar diminish and will thus know he is making progress.
Traditional biofeedback methods employ such mechanisms as analog meters, computer-generated displays, targets shown in cross hairs, acoustic tones and audio beat frequencies to indicate to the subject the values of the parameters being monitored.
Biofeedback is commonly performed by a biofeedback technician, who directs the subject verbally to achieve a state of calm by coaching him to develop a mental image of a relaxing scene. Unfortunately, it can be difficult to relax during such a session because the subject is forced to concentrate on a computer display or audio tone to gauge his progress. That is, the result or display viewed by the subject is not in itself calming, and may actually interfere with the desired objective.
Biofeedback can be used to treat migraine and tension headaches, pain disorders such as temporomandibular joint dysfunction (TMJ) and myofascial syndromes, musculoskeletal tension, hypertension, anxiety and panic disorders, asthma, dyspepsia, and other conditions that can be controlled by reducing muscular tension, inducing a state of calm or stabilizing autonomic function. Biofeedback can be used both for treatment and prevention of such syndromes.
Biofeedback devices and methods comprising visual displays are known in the prior art. Ross U.S. Pat. Nos. 3,837,331 and 3,967,616 teach use of a "transducing means" for exhibiting sensory signal output to the human subject, which may include a matrix of numbered lamps, slides projected on a screen, or an audible chime. Hidalgo-Briceno U.S. Pat. No. 3,855,998 discloses an entertainment device that monitors electrophysiological parameters of a human subject and presents "audiovisual stimulation" comprising passages of music, flashing lights or projected images intended to place the subject in a desired psychological state. The Hidalgo-Briceno invention, while it receives electrical signals from the subject, is not a biofeedback device because the subject is not guided by stimuli to modify his own physiological parameters, providing no feedback within the system. Cornellier et al. U.S. Pat. No. 4,683,891 teaches use of a visual display to indicate the values of a subject's physiological parameters at the point where stress is induced during performance of a goal-oriented task.
A number of prior art biofeedback devices employ purely audio feedback to the subject. Silva et al. U.S. Pat. No. 3,875,930 teaches using a fixed audio signal that decays to silence as an indication that the desired brain wave waveform has been achieved. Spector U.S. Pat. No. 4,776,323 teaches playing sounds through headphones to induce relaxation in a subject for the purpose of creating a calm state that can then be interrupted by high amplitude noises to cause stress. Knispel et al. U.S. Pat. No. 4,883,067 teaches a method of transforming brain wave activity into musical sound, which is fed back to the subject via headphones.
Numerous prior art devices combine audio and visual feedback. Glynn et al. U.S. Pat. No. 3,942,516 teaches simultaneous monitoring of a plurality of electrophysiological parameters to produce a single audiovisual output for feedback. Fehmi et al. U.S. Pat. No. 3,978,847 teaches using audio tones and a light that increases in amplitude and stroboscopic frequency as the frequency of the subject's brain waves increases. Clegg et al. U.S. Pat. No. 4,823,808 teaches a method for treating eating disorders by measuring parameters of the gastrointestinal tract and providing indications of gastric activity by visual and audio means, such as by amplifying stomach noises. Ohsuga et al. U.S. Pat. No. 4,896,675 teaches providing graphs of physiological parameters and simultaneously generating a sound pattern to be used by the subject to control his rate of respiration. Ayers U.S. Pat. Nos. 4,919,143 and 5,024,235 teach a sound and light box in addition to graph waveforms as output from a biofeedback system. Hardt U.S. Pat. No. 4,928,704 teaches combining tone feedback with display of digital data to the subject. Hillsman U.S. Pat. No. 4,984,158 teaches auditory prompts and use of visual graphs for instructing subjects to use a metered dose inhalation system. Carter et al. U.S. Pat. No. 5,036,858 teaches use of light goggles and headphones to convey beat signals to a subject indicative of how much his brain wave frequency differs from a desired frequency. Gavish U.S. Pat. No. 5,076,281 teaches using synthesized sound patterns and optical effects indicative of parameters of biorhythmic activity.
Freeman U.S. Pat. No. 3,916,876 teaches measurement of muscle tension in two selected muscles while the subject watches electrical meters displaying the tension measurements and other quantities derived from them. There is no audio or visual feedback other than meter readings.
Brady U.S. Pat. Nos. 4,056,805 and 4,140,997 disclose a video display comprising a matrix of colored lights that is controlled in response to brain waves. Brady's invention, however, does not comprise a biofeedback system. Brady's invention is directed to conveying a visual indication of a subject's response to sound, particularly music. Shiga U.S. Pat. No. 4,354,505 teaches measurement of the length of time a subject has remained in a relaxed state by displaying numerals indicative of this length. Ochs U.S. Pat. No. 4,461,301 teaches display of numerical indications dependent on the values of monitored electrophysiological parameters. Leuner et al. U.S. Pat. No. 4,665,926 teaches a system for measuring a person's relaxation state, but in which displayed information is not fed back to the subject but is instead monitored by a technician.
It is a drawback of prior art biofeedback devices and methods that the feedback provided to the subject is merely a display of values of physiological parameters or an indication of how successful the subject has been in achieving his goal. They do not provide a target, desirable in itself, to assist in the attainment of success. In fact, the prior art devices utilize feedback means that can actually interfere with the desired objective by forcing the subject to concentrate on a wave tracing, flashing light or blip on an oscilloscope screen in order to gauge his progress. In prior art methods, the subject must generally be coaxed by an assistant into imagining a relaxing scene or locale in order to alter his electrophysiological responses.
The objects of the present invention are to improve the efficacy of biofeedback by eliminating dependence on stress-inducing visual or audio targets on which the subject must concentrate; to determine an effective weighted combination of physiological potentials for a given subject that can be used in conditioning biofeedback response; to monitor and record a subject's progress through one or more biofeedback treatments by storing and reporting data concerning the subject's responses on a digital computer so that the combination of physiological potentials monitored can be altered to maximize the effectiveness of the treatment; to provide a means by which a subject's success in controlling his physiological potentials causes presentation of a graded sequence of pleasant scenes of successively greater video and audio clarity, specifically by controlling the relative speed of motion of the video portion and controlling the content of the audio portion; to train the subject through biofeedback to induce self-relaxation subsequent to a training session without having to rely on a machine for audiovisual response; and to develop a conditioned response on the part of a subject so that he can induce in himself a desired psychoneurological state by recalling to memory one or more prestored audiovisual scenes.